High density hydrocarbon fuel is an important component of liquid propellants for aircrafts, being a key for providing power guarantee for aircrafts such as airplanes, missiles and rockets, and thus, the quality of the fuel will decide the flight performances (including flying range, flying speed, and effective loads) of the aircrafts. For an aerospace aircraft having a definitive volume, the higher the density of the liquid fuel is, the higher the mass of the fuel carried by the aircraft is; the higher the volumetric heat value of the fuel, the higher the energy released by consuming per unit volume of the fuel. These characteristics of the fuel will be more beneficial to the performances of the aircrafts in various aspects. Alternatively, on the premise of keeping the performances of aircrafts unchanged, using a high density fuel can reduce the volume of used oil tanks, minimize the volume of the aircrafts, and increase the penetration ability and mobility of the aircrafts.
Fused-ring alkane fuel is a kind of liquid fuel having high density, high heat value, low freezing point and high thermal stability. For example, decalin has a molecular density of 0.88 g/mL, a freezing point of less than −30° C., and a net combustion heat value of more than 37.4 MJ/L, and it is excellent in thermal stability. Thus, this material is a main component of high density thermally stable jet fuels (e.g., JP-900). There are many reports regarding processes of preparing the fused-cycle alkane fuel molecules. In the document “Sustainable Chemistry & Engineering, 2016, 4, 6160” in the document ACS reports, by taking cyclopentanol as a raw material, the cyclopentanol is catalytically dehydrated to produce cyclopentene, then the cyclopentene takes an intermolecular alkylation reaction to produce a fuel precursor such as decalin, and at last, the fuel precursor is hydrogenated under high pressure to produce a mixture of decalin (77 wt %) and C15 alkanes, the mixture having a density of 0.90 g/mL. In the document “Chemical Engineering Science, 2018, 180, 64”, concentrated sulfuric acid is utilized to catalyze the one-pot reaction of a cyclic alcohol and a branched cycloalkane to perform continuous dehydration, alkylation, rearrangement and hydrogen transfer, thereby to obtain branched naphthalene alkanes having a density of 0.88 g/mL or above and a freezing point as low as −110° C. However, these processes have complicated procedures and complex operations, or they will produce strong corrosions to associated apparatus, or they have a low selectivity to fused-ring alkane products. Thus, it is a challenge to produce fused-ring multi-ring alkane fuel with high selectivity under mild conditions.